How to: Ratio t test

Prism can easily perform a ratio t test from two columns of data entered into a Column data table.

1.Create a column data table and enter two columns of data, with matched values on the same row. For example:

Control

Treated

4.2

8.7

2.5

4.9

6.5

13.1

2.From the data table, click on the toolbar.

3.Choose t tests from the list of column analyses.

4.On the first (Experimental Design) tab of t test dialog, make these choices:

•Experimental design: Paired

•Assume Gaussian distribution: Yes. (Actually you are assuming a lognormal distribution of differences.)

•Choose test: Ratio paired t test

5.On the second tab of the t test dialog, choose to compute Treated - Control, rather than Control - Treated. Note that even though the ratio t test computes a ratio, the choice on the dialog is worded as if the values were subtracted.